Not trying to be rude or anything, guys, but this isn't really the place for fish care advice...
Keep the comments on the craft itself. The fish in these containers have healthy fins and beautiful coloration and the owners that make these tanks obviously care about the fish or else this really creative tank wouldnt have been made. So if you like how the colors compliment each other really well or if you think that some greenery would be good or if it inspires you to make a fish tank out of a lamp, thats awesome and you should comment here.
Well I am sorry, but if it is cruel, it is cruel. It could
be a healthy looking fish because it just came from the pet shop, not because it is happy living in that pot.
If there was a craft to admire that involved a person being shut in a small glass box - but the box was beautifully made - I would expect people to be posting "get that person out of that box!"